“It is possible she put her head in something but extraordinarily unlikely, given the way it has splashed upwards,” vet David Rendle told H&H. “I’d say it was acid, thrown in her face.”

The pony is also suffering with other chronic issues – she is very anaemic and has a high worm burden and lice, “typical of this type of abandoned pony”, Mr Rendle said – but the facial injuries are the biggest concern.

“The skin from her eyes downwards is going to come off,” he said, adding that the filly may need skin grafts.

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“She’s having to have blood transfusions to replace the protein she’s losing through her damaged skin and to reverse the anaemia.

“The worry will be if she loses her eyelids as she’ll then be in chronic pain from ulceration of the surface of her eyes, and that’s probably not feasible.

“But while she’s bright and happy, it seems right and fair to keep treating her.”

Mr Rendle said the pony, who he and his colleagues were told was eight months old but is thought to be younger, is “very bright” considering the severity of her wounds, and eating well.

“She’s tough,” he added. “If she shows signs of suffering, we’d have to re-evaluate whether it’s fair to continue treatment but we think the end justifies the means.”

Mr Rendle said there are two issues of which to raise awareness: abandoning horses and deliberately harming them, the latter of which is luckily far more rare.

“The fact it’s deliberate is so abhorrent,” he added. “What business has anyone got to do that to an animal? As vets we see wounds from accidents and we can take that but when you know someone’s deliberately inflicted this pain on her, and then she stands there and takes it as we inflict more pain as we try to treat it – it turns your stomach.”

Treatment is currently being funded by the RSPCA and Rainbow Equine Hospital but anyone who would be in a position to help with the pony’s ongoing treatment and nursing care is asked to visit the Rainbow Equine Hospital Facebook pagefor further information.

For all the latest news analysis, competition reports, interviews, features and much more, don’t miss Horse & Hound magazine, on sale every Thursday.

Also in this Thursday’s edition, don’t miss our full Badminton preview, including cross-country course walk with Mary King and full form guide for every horse and rider.